Admission N-terminal pro-brain natriuretic peptide and its interaction with admission troponin T and ST segment resolution for early risk stratification in ST elevation myocardial infarction

Objective: To assess the long term prognostic value of N-terminal pro-brain natriuretic peptide (NT-proBNP) on admission and its prognostic interaction with both admission troponin T (TnT) concentrations and resolution of ST segment elevation in fibrinolytic treated ST elevation myocardial infarction (STEMI). Design and setting: Substudy of the ASSENT ( assessment of the safety and efficacy of a new thrombolytic) -2 and ASSENT-PLUS trials. Patients: NT-proBNP and TnT concentrations were determined on admission in 782 patients. According to NT-proBNP concentrations, patients were divided into three groups: normal concentration ( for patients <= 65 years, <= 184 ng/l and <= 268 ng/l and for those > 65 years, <= 269 ng/l and <= 391 ng/l in men and women, respectively); higher than normal but less than the median concentration ( 742 ng/l); and above the median concentration. For TnT, a cut off of 0.1 mg/l was used. Of the 782 patients, 456 had ST segment resolution (< 50% or >= 50%) at 60 minutes calculated from ST monitoring. Main outcome measures: All cause one year mortality. Results: One year mortality increased stepwise according to increasing concentrations of NT-proBNP (3.4%, 6.5%, and 23.5%, respectively, p < 0.001). In receiver operating characteristic analysis, NT-proBNP strongly trended to be associated more with mortality than TnT and time to 50% ST resolution ( area under the curve 0.81, 95% confidence interval (Cl) 0.72 to 0.9, 0.67, 95% CI 0.56 to 0.79, and 0.66, 95% CI 0.56 to 0.77, respectively). In a multivariable analysis adjusted for baseline risk factors and TnT, both raised NT-proBNP and ST resolution, 50% were independently associated with higher one year mortality, whereas raised TnT contributed independently only before information on ST resolution was added to the model. Conclusion: Admission NT-proBNP is a strong independent predictor of mortality and gives, together with 50% ST resolution at 60 minutes, important prognostic information even after adjustment for TnT and baseline characteristics in STEMI.